I'll double-check the actual filesystem type (v1 or v2.. I think
it was

newfs -o time -O 2) tonight, as it's paused again.

Looks like you are using softdep - I fixed a problem yesterday that
could
have caused this. Can you please update your kernel sources and try
again?

I get something similar since 4.99.48 - processes accessing anything
on an lfs filesystem get stuck after a while, waiting on lfs_sdir. I
thought it's an SMP problem ( first noticed it on a dual G4 ) but now
I see it on a sparc64 box as well.